Explained: What is Aditya-L1 mission and how it will help us unravel Sun's mysteries

Riding high on the successful moon landing of Chandrayaan-3, ISRO is now aiming for the Sun as it has set its eyes on the launch of a solar mission, anticipated to take place on September 2.

Aditya-L1 spacecraft is designed for providing remote observations of the solar corona and in situ observations of the solar wind at L1 (Sun-Earth Lagrangian point), which is about 1.5 million kilometres from the earth.

It will be the first dedicated Indian space mission for observations of the Sun to be launched by the Bengaluru-headquartered space agency. The satellite, realised at UR Rao Satellite Centre here, arrived at the ISRO’s spaceport of Sriharikota in Andhra Pradesh, a couple of weeks ago.

The Sun is the nearest star and the largest object in the solar system. It is estimated to be about 4.5 billion years old. Earth’s distance from the hot glowing ball of hydrogen and helium gases is about 150 million km, according to ISRO. The visible surface of the Sun, known as the photosphere, is relatively cool and has a temperature of about 5,500°C. The outermost layer of the Sun is called the corona.

What is the Aditya-L1 mission?

Aditya-L1 spacecraft is designed to provide remote observations of the solar corona and study the solar atmosphere. The spacecraft will extensively study the solar winds which can cause disturbance on the earth and are commonly seen as “auroras”.

Named after the Hindi word for the sun, the spacecraft is India’s first space-based solar probe. In the long term, data from the mission could help better understand the sun’s impact on the earth’s climate patterns.

According to ISRO’s official website, it’s a one-of-kind mission to study the sun’s outer atmospheric dynamics as well as the factors that drive weather in space. The spacecraft is expected to be placed in a halo orbit around the Lagrange point 1 (L1) of the Sun-Earth systems, which is about 1.5 million kilometres from the earth.

A satellite placed in the halo orbit around the L1 point offers the major advantage of continuously viewing the Sun without any eclipses. “This will provide a greater advantage of observing the solar activities and its effect on space weather in real-time,” explains the website. The spacecraft will carry seven payloads to observe the sun’s outermost layers, including the photosphere, chromosphere, and the outermost layers – using electromagnetic and particle and magnetic field detectors.

Using the special vantage point L1, four payloads directly view the sun and the remaining three payloads carry out in-situ studies of particles and fields at the L1, thus providing important scientific studies of the propagatory effect of solar dynamics in the interplanetary medium.

“The Solar Ultraviolet Imaging Telescopes (SUITs) of Aditya L1 payloads are expected to provide most crucial information to understand the problem of coronal heating, coronal mass ejection, pre-flare and flare activities and their characteristics, dynamics of space weather, propagation of particle and fields etc,” ISRO said.

In space terms, payload refers to those elements of the spacecraft specifically dedicated to producing mission data and then relaying that data back to the earth.

How far will Aditya-L1 travel?

To be launched aboard a PSLV-XL vehicle, the Aditya-L1 spacecraft will travel 1.5 million km in about four months to study the sun’s atmosphere. After the launch, it will take 125 days from the earth to reach Lagrange point 1 (L1).

It will head to a kind of parking lot in space where objects tend to stay put because of balancing gravitational forces, reducing fuel consumption for the spacecraft. Those positions are called Lagrange Points, named after Italian-French mathematician Joseph-Louis Lagrange.

The spacecraft will leave the gravitational Sphere of Influence (SOI) of the earth as it moves toward L1. The gravitational pulls of the Sun and Earth are balanced at the L1 point, which is a stable place.

How much does the mission cost?

In 2019, the government sanctioned the equivalent of about $46 million for the Aditya-L1 mission. However, ISRO has not given an official update on costs.

Initially, the mission was planned as an experimental project with a small 400 kg low-Earth orbiting satellite to study the solar corona with a budget of Rs 3 crore. Now, the scope of the project is expanded to be a comprehensive solar and space environment observatory to be placed at the L1 point.

The Indian space agency has earned a reputation for world-beating cost competitiveness in space engineering that executives and planners expect will boost its now-privatised space industry.

The Chandrayaan-3 mission, which landed a spacecraft on the lunar South Pole, had a budget of about $75 million.

What are the mission's main objectives?

The major science objectives of the Aditya-L1 mission are: Study of solar upper atmospheric (chromosphere and corona) dynamics; study of chromospheric and coronal heating, physics of the partially ionised plasma, initiation of the coronal mass ejections, and flares; observe the in-situ particle and plasma environment providing data for the study of particle dynamics from the sun.

They also include physics of solar corona and its heating mechanism; diagnostics of the coronal and coronal loops plasma; temperature, velocity and density; development, dynamics and origin of Coronal Mass Ejections (CMEs); identify the sequence of processes that occur at multiple layers (chromosphere, base and extended corona) which eventually leads to solar eruptive events; magnetic field topology and magnetic field measurements in the solar corona; drivers for space weather (origin, composition and dynamics of solar wind).

How will the studies conducted by Aditya-L1 help us?

It will enable us to comprehend the Sun and how it affects Earth better. The information acquired from the mission will help us better understand and predict space weather phenomena like solar flares, CMEs, solar wind, and other phenomena that have an impact on the operation of space technology near or on Earth as well as other planets.

When it comes to the Earth, a magnetic disturbance can occur when the Earth’s magnetic field interacts with the field delivered by the CME. Space weather events have the potential to significantly affect our satellites, communication networks, and power grids. We can better safeguard ourselves from these occurrences by comprehending the sun